And while acts of deception cannot be condoned, it is also important to note that the documents obtained by Gleick provide an insight into how some of those groups that are fundamentally opposed to reducing emissions of greenhouse gases attempt to convey the impression that their arguments are founded on science rather than on ideology.

The Heartland Institute states on its website that its mission is "to discover, develop, and promote free-market solutions to social and economic problems", and that the aim of its work on climate change is to promote "market-based, rather than government-based, solutions to environmental problems". The Institute has been one of the most active lobbyists against policies in the United States to curb emissions, primarily by attempting to undermine confidence in the findings of scientific research that climate change is driven mainly by human activities.

"Many people lament the absence of educational material suitable for K-12 [kindergarten to 12th grade] students on global warming that isn't alarmist or overtly political. Heartland has tried to make material available to teachers, but has had only limited success. Principals and teachers are heavily biased toward the alarmist perspective."

The document then suggests that it will pay Dr David Wojick, described as "a consultant with the Office of Scientific and Technical Information at the US Department of Energy in the area of information and communication science", to produce teaching materials which emphasise controversy and uncertainty:

"Wojick would produce modules for Grades 7-9 on environmental impact ("environmental impact is often difficult to determine. For example there is a major controversy over whether or not humans are changing the weather"), for Grade 6 on water resources and weather systems, and so on."

This, of course, is a biased and distorted representation of current scientific knowledge, and conflicts with the approach to school lessons outlined by a recent workshop on climate change education, hosted by the United States National Academy of Sciences, which begins with the statement: "The global scientific and policy community now unequivocally accepts that human activities cause global climate change".

However, the emphasis on uncertainty and controversy is very much in line with another famous leaked document, the so-called Luntz memo, which came to light in 2003. It was prepared by Frank Luntz, the favourite opinion pollster of President George W Bush, and contained advice for Republican activists on how to talk to potential voters about environment issues. On climate change, the memo offers the following recommendation:

"The scientific debate remains open. Voters believe that there is no consensus about global warming within the scientific community. Should the public come to believe that the scientific issues are settled, their views about global warming will change accordingly. Therefore, you need to continue to make the lack of scientific certainty a primary issue in the debate, and defer to scientists and other experts in the field."

The strategy of playing up controversy and uncertainty to undermine confidence in well-established scientific findings was pioneered by the tobacco industry to avoid and delay regulation of its products. As Naomi Oreskes and Erik Conway point out in their book Merchants of Doubt:

"Doubt is crucial to science – in the version we call curiosity or healthy scepticism, it drives science forward – but it also makes science vulnerable to misrepresentation, because it is easy to take uncertainties out of context and create the impression that everything is unresolved. This was the tobacco industry's key insight: that you could use normal scientific uncertainty to undermine the status of actual scientific knowledge."

The Heartland Institute documents also contain details of another activity designed to give its ideological campaign against emissions regulations a veneer of scientific credibility. It notes that the Heartland Institute sponsors the "Nongovernmental International Panel on Climate Change (NIPCC), an international network of scientists who write and speak out on climate change".

Again this echoes an approach outlined in the Luntz memo:

"You need to be even more active in recruiting experts who are sympathetic to your view, and much more active in making them part of your message. People are much more willing to trust scientists, engineers, and other leading research professionals, and less willing to trust politicians. If you wish to challenge the prevailing wisdom about global warming, it is more effective to have professionals making the case than politicians."

And it also copies the tactics of cigarette companies which, according to Oreskes and Conway, hired a renowned geneticist in the 1950s to "head the Tobacco Industry Research Committee and spearhead the effort to foster the impression of debate, primarily by promoting the work of scientists whose views might be useful to the industry".

The Heartland Institute documents demonstrate once again how those driven by ideological dogma or vested commercial interests attempt to hide their true motives behind a facade of false controversy and uncertainty in science.